Curable silicone compositions that cure by the hydrosilylation reaction exhibit an excellent heat resistance, excellent cold resistance, and excellent electrical insulation performance and as a result are widely used in electrical and electronic applications. The cured products provided by the cure of these compositions generally have a large thermal expansion coefficient. As a result, when such a cured product is used to form a single article with another member, strain may be generated at the cured product/other member interface accompanying temperature variations, and delamination may occur or the single article may itself undergo rupture. The incorporation of large amounts of an inorganic filler into curable silicone compositions in order to lower the thermal expansion coefficient of the cured product is well known, but accrues the problems of a substantial increase in the viscosity of the resulting composition and diminished handling characteristics therefore and an impaired flexibility for the resulting cured product.
Curable silicone compositions that provide a cured product with a reduced thermal expansion coefficient can be exemplified by the following: a curable silicone composition comprising: a straight-chain organopolysiloxane that contains at least two alkenyl groups in one molecule; a branched-chain organopolysiloxane that contains at least three alkenyl groups in one molecule; a branched-chain organopolysiloxane that contains at least three silicon-bonded hydrogen atoms in one molecule; and a hydrosilylation reaction catalyst (refer to Japanese Unexamined Patent Application Publication (hereinafter referred to as “Kokai”) 2006-335857); and a curable silicone composition comprising: a branched-chain organopolysiloxane that contains alkenyl and phenyl groups; a straight-chain organopolysiloxane that contains at least two alkenyl groups in one molecule; a branched-chain organopolysiloxane that contains at least three silicon-bonded hydrogen atoms in one molecule; and a hydrosilylation reaction catalyst (refer to Kokai 2007-39483).
However, even these curable silicone compositions have not been able to provide a satisfactory reduction in the thermal expansion coefficient of the cured product.
An object of the present invention is to provide a curable silicone composition that forms a cured product that has a small thermal expansion coefficient. A further object of the present invention is to provide a cured product that has a small thermal expansion coefficient.